1. Field of the Invention
This disclosure relates to DVD menu navigation, and more specifically to methods for navigating a DVD menu using a maximum of one or two user input buttons.
2. Description of the Prior Art
The DVD Video format provides interactive features for a user during a presentation (e.g. movie). This allows browsing of the disc content using animated menus and other interactions of the user while watching the disc content. The DVD Video specification [DVD,96], Annex J, specifies a number of mandatory user operations to allow the interactive browsing of disc content. These operations include a mandatory 4-directional button navigation in menus ((Upper_Button_Select( ), Lower_Button_Select( ), Left_Button_Select( ), Right_Button_Select( )).
The internal DVD data for these buttons in menus are based on each button having assigned data for the four neighboring buttons (up/down/left/right; adjacent button information, AJBTN_POSI in PCI; [DVD,96], 4.4.3.4.(b)). These data are generated by the disc author and cannot being predicted. It can be quite complicated as the state machine 10 illustrated in FIG. 1 shows and have no correlation with the button position on the screen.
The DVD Video Specification ([DVD,96]) was designed mainly for home use and there was originally no detailed intention of mobile or automotive use. Hence the interactive features of DVD Video were designed maximizing the interactive features and thus the mandatory number of user inputs (e.g. key pad buttons) is necessary to operate the disc menu functions.
In restricted environment (mobile or automotive use) there might not be enough user controls (e.g. key pad buttons) to map all four directions on separate buttons. An alternative input method may use buttons with dual functions (e.g. short press=first function; long press=alternate function) or switching the key pad functions to an alternate function by a special selection button (e.g. like the Shift or Ctrl button on PC keyboards). This alternate input may be difficult to operate or, in the later version, require an additional Shift key, hence it fails to improve the situation.